Conversion of hydrocarbon oils



June 24, 1941. K. SWARTWOOD CONVERSION OF HYDROCARBON OILS Original Filed Jan. 19, 1935 1? mm ZwQZOU INVENTOR KENNETH SWARTWOOD1 EUQEIU OZCKELMW TORNEY Patented June 2 4, 1941 CONVERSION OF HYDROCARBON OILS Kenneth Swartwood, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application January 19, 1935, Serial No. 2,477 Renewed May 15, 1939 This invention particularly refers to an im- 7 Claims.

proved process for the conversion of hydrocarbon oils of relatively wide boiling range (comprising the reflux condensate recovered by fractionation of the final vaporous products of the process) followed by separation of the products, together i with the hydrocarbon oil charging stock for the process, into vaporous and heavy liquid products, each of which are separately subjected to further conversion under definitely controlled more severe conversion conditions than those to which said reflux condensate is subjected and the resulting vaporous products subjected to fractionation for the formation of said reflux condensate and the recovery of desirable low-boiling liquid 7 products such as motor fuel of high antiknock value.

In one embodiment, the invention comprises subjecting oil comprising intermediate liquid conversion products of the process to conversion temperature at superatmospheric pressure in a heating coil, introducing the resulting heated products into a separating chamber to which hydrocarbon oil charging stock for the process is supplied and wherein the charging stock is subjected to appreciable vaporization, separating the vaporous and heavy liquid components of the resulting commingled charging stock and conversion products in said separating chamber, withdrawing said heavy liquids from the separating chamber and subjecting the same to a higher conversion temperature at superatmospheric pressure in a separateheating coil without allowing the oil to remain in the heating coil fora sumcient length of time to permit any substantial formation and deposition of coke in this zone, introducing the highly heated. oil from said separate heating coil into a coking chamber wherein it is reduced to substantially dry coke, subjecting the vaporous products from the coking chamber, together with the vaporous products from said separating chamber, after the removal therefrom of undesirable high-boiling components, including entrained heavy liquids and similar high coke-forming materials, to further conversion in another separate heating coil at an appreciablyhigher conversion temperature than that employed in the first mentioned heating coil, separating from :the resulting products high-boiling polymers and similar residual liquids, subjecting the remaining vapors to fractionation whereby their insufficiently converted components are condensed as said intermediate liquid conversion products of the process, supplying the latter to the first mentioned heating coil for conversion, subjecting fractionated vapors of the desired end-boiling point to condensation and collecting and separating the resulting distillate and gas.

Various modifications of the specific embodiment of the present invention above outlined may be employed without departing from the scope of the invention. Some of these modifications are illustrated in the accompanying diagrammatic drawing and will be described in connection with the following description of the drawing. The drawing illustrates one specific form of apparatus in which the process of the invention may be accomplished.

Heating coil 1 is located'within a furnace 2 of any suitable form by means of which the oil supplied to the heating coil, in the manner to be later more fully described, is subjected to the desired conversion temperature, preferably at a substantial superatmospheric pressure. The resulting heated products are discharged from the heating coil through line 3 and valve 4 into vaporizing and separating chamber 5.

Hydrocarbon oil charging stock for the process, comprising an oil of either relatively low-boiling or high-boiling characteristics or an oil of relatively wide boiling range, is supplied through line 6 and valve 7 to pump 3 by means of which it is fed through line it and is directed through line H, valve i2, heat exchanger i3, line it, valve 15, heat exchanger coil i6, line it and valve 18 into chamber ii.

Chamber 5 is a zone of vaporization and separation wherein the charging stock for the process is commingled with the hot vaporous conversion products from heating coil l and wherein the resulting commingled materials are separated into vaporous products and liquids of relatively high-boiling nature. Chamber 5 may be operated at any desired pressure ranging from substantially atmospheric to a superatmospheric pressure substantially the same as that employed at the outlet from the preceding heating coil. The pressure employed in this zone and the temperature to which the charging stock is preheated, prior to its introduction thereto, serve as control means to insure .the desired degree of vaporization for the particular charging stock employed and the desired separation of vaporous and liquid conversion products. Preferably a sufficient superatmospheric pressure is employed in chamber 5 to obviate the use of a pump or compressor for handling the vaporous products from this zone,

which are withdrawn from the upper portion of the chamber through line l9 and valve 20 to heat exchanger I3 wherefrom the remaining vapors are directed through line 2| and valve 22 to further conversion in heating coil 23.

Heat exchanger [3 may serve, as already described, as a means of preheating the charging stock and, by efiecting partial cooling of the vaporous products from chamber 5, also serves as a means of separating therefrom undesirable high-boiling components such as entrained or dissolved heavy liquids and similar high cokeforming materials. The high-boiling liquids separated from the vaporous products in heat exchanger l3 may be withdrawn from the lower portion of this zone through line 24 and valve 25 and may be withdrawn from the system to cooling and storage or may be disposed of in any other suitable manner.

Heating coil 23 is located within a furnace 26 of any suitable form by means of which the vaporous products supplied to this zone are heated to the desired conversion temperature which preferably is appreciably higher than the temperature employed in heating coil I. The pressure employed in heating coil 23 is preferably somewhat less than that employed in chamber in order to insure passage of the vapors through the heating coil without the use of a pump or compressor.

The highly heated products are discharged from heating coil 23 through line 27 and valve 28 into chamber 29 wherein high-boiling materials such as heavy polymerization products and residual liquid are separated from the lower boiling vaporous products.

Heat exchanger coil I6, through which charging stock for the process may pass as previously described and subjected therein to preheating, serves as a means of partially cooling the vaporous products in this zone to assist the removal therefrom of said high-boiling components and to retard or arrest their further conversion. It is also specifically within the scope of the present invention to effect the desired degree of cooling in chamber 29 for the purpose of retarding or preventing further conversion of the heated products from heating coil 23 and for the purpose of assisting the desired separation of vaporous and liquid products in this zone by supplying thereto a suitable cooling oil. Provision is made, in the particular case here illustrated, for supplying regulated quantities of the reflux condensate from fractionator 36 to the upper portion of chamber 29 through line 38 and valve 3i.

The high-boiling liquids separated from the vaporous conversion products from heating coil 23 in chamber 29 may be withdrawn from the lower portion of this zone through line 32 and valve 33 and may be directed to cooling and storage. Vaporous products are withdrawn from the upper portion of chamber 29 through line 34 and valve 35 and are subjected to fractionation version in heating coil I, in the manner pre-,

Viously described.

Fractionated vapors of the desired end-boiling point are directed from the upper portion of fractionator 36 through line 42 and valve 43 and are subjected to condensation and cooling in condenser 44. The resulting distillate and uncondensable gas passes through line 45 and valve 46 to collection and separation in receiver 4?. Gas may be released from the receiver through line 48 and valve 4S. Distillate may be withdrawn from receiver 4? through line 53 and valve 5| to storage or to any desired further treatment.

The high-boiling components of the charging stock and of the conversion products from heating coil 1, separated from the vaporous components of the commingled materials in chamber 5, are Withdrawn from the lower portion of this zone through line 52 and valve 53 to pump 54 by means of which they are directed through line 55 and valve 56 to heating coil 51. A furnace 58 of any suitable form supplies the required heat to the relatively heavy oil passing through heating coil 51 to subject the same to the desired conversion temperature which preferably is appreciably higher than that employed in heating coil I. Although heating coil 51 and furnace 58 are shown in a diagrammatic manner in the drawing they are preferably of such form that the oil supplied thereto is quickly heated to the desired relatively high conversion temperature without allowing it to remain in the heating coil and communicating lines for a sufiicient length of time to permit any substantial formation and deposition of coke therein. The stream of heated oil is discharged from heating coil 57 through line 59 and may be directed through one or a plurality of suitable branch lines 60 controlled by valves 6| into coking chamber 62 and/or through one or a plurality of similar branch lines 6 controlled by valves 6| into coking chamber 62', entering either or both of these zones at any desired point or plurality of points.

Chambers 62 and 62 are similar coking zones wherein the highly heated, high-boiling liquids from heating coil 5'! are reduced to substantially dry coke. It will be understood that although only two coking chambers are shown in the draw ing one or any desired number of a plurality of these zones may be employed, when desired, and when a plurality is employed the chambers may be operated simultaneously or, preferably, are alternately operated, cleaned and prepared for further operation in order that the coking stage, in common with the rest of the system may be operated continuously. Chamber 62 and 62 are provided with suitable drain lines 63 and 63', respectively, controlled by the respective valves 64 and 64', which may also serve as a means of introducing steam, water or any other suitable cooling medium into the chamber, after its operation is completed and after it has been isolated from the rest of the system, in order to hasten cooling and facilitate the removal of coke from the chamber.

Vaporous products are withdrawn from the respective coking chambers 62 and 62' through lines 65 and 65', controlled by the respective valves 66 and 66, and are directed through line- .68 and valve 69 to heat exchanger i3, together with the vaporous products from chamber 5; any undesirable high boiling components such as entrained or dissolved tars and similar heavy liquids being separated from the vaporous products from the coking chambers in the heat exchanger while the remaining vaporous products pass to further conversion in heating coil 23, in the manner previously described. The preferred range of operating conditions which may be employed to accomplish the purpose of the present invention in an apparatus such as illustrated and above described may be approximately as follows: The heating coil to which the intermediate liquid products ofthe process (reflux condensate) are supplied may utilize a conversion temperature, measured at theoutlet therefrom, of the order of 800 to 950 F., preferably with a superatmospherio pressure at this point in the system of from 100 to 500 pounds, or thereabouts, per square inch. A superatmospheric pressure ranging from substantially the same as that employed in the preceding heating coil down to substantially atmospheric pressure may be utilized in the vaporizing and separating chamber, although a superatmospheric pressure suflicient to effect the passage of the vaporous products in this zone through the succeeding heating coil without the use of a pump or compressor is preferred. The heating coil to which the vaporous products from the first cracking stage of the system, as well as, from the coking zone, are supplied for further conversion may utilize an outlet temperature ranging, for example, from 950 to 1100? F., preferably with substantially atmospheric or a relatively low superatmosp-heric pressure up to 100 pounds, or thereabouts, per square inchat this point of the system although higher pressures up to 500 pounds, or more, per square inch may be employed in this zone, when desired, particularly when a high pressure of the same order is employed in the preceding vaporizing and separating chamber. The pressures employed in the separating chamber succeeding the last mentioned heating coil end in thefractionating, condensing and collecting portions of the system maybe substantially the same or somewhat lower than the pressure employed in said heating coil.

The heating coil of the coking stage of the system preferably employs a relatively high conversion temperature of the order of 900 to 1000 F. and, as previously indicated, the velocity of the oil and rates of heating in this zone are sufficiently high to prevent any substantial formation and deposition of coke 'prior to the introduction of the heated oil in the coking chamber. The pressure employed in the heating coil of the coking system may range, for example, from substantially atmospheric pressure to 200 pounds, or more, per square inch, superatmospheric pressure and the pressure employed in this zone may be substantially equalized or reduced in the coking chamber, as desired.

As a specific example of one operation of the process of the present invention, as it may be accomplished in an apparatus such as illustrated and above described, the charging stock is a Wyoming crude of about 20.7" A. P. I. gravity, containing approximately 17 per cent of material boiling up to 437 F., which is supplied to the vaporizing and separating chamber of the primary cracking stage of the system. The intermediate liquid conversion products, comprising reflux condensate from the fractionator of the system, are subjected in the heating coil of the primary cracking stage to a conversion temperature, measured at the outlet therefrom, of approximately 930 F. at a superatmospheric pressure of about 250 pounds per square inch, which is reduced in the succeeding vaporizing and sep- CJI ,perature of approximately 700 arating chamber to a superatmospheric pressure of about 150 pounds per square inch. The heavy liquid products from the vaporizing and separating chamber are quickly heated in a separate heating coil to an outlet conversion temperature of approximately 980 F. at a superatmospheric pressure of about 150 pounds per square inch and are introduced into alternately operated coking chambers maintained at substantially the same pressure. High-boiling components, including tars and similar high coke-forming liquids, are removed from the vaporous products from the coking zone and from the vaporizing and separating chamber and are returned to the heating coil of the coking stage of the system. The remaining vaporous products from the vaporizing and separating chamber and from the coking zone are subjected in another separate heating coil to an outlet conversion temperature of approximately 1050 F. at a superatmospheric pressure of about pounds per square inch. This pressure is reduced in the succeeding separating chamber to approximately 30 pounds, per square inch, superatmospheric pressure, which is substantially equalized in the succeeding fractionvatlng, condensing and collecting portions of the system. A regulated portion of the final light distillate product of the process is returned to commingle with and cool the stream of hot conversion products from the last mentioned heating coil sufiiciently to prevent any appreciable further conversion thereof and a regulated portion of the reflux condensate from the fractionator of the system is supplied to the upper por tion of the separating chamber following the last mentioned heating coil. The charging stock is preheated, prior to its introduction into the vaporizing and separating chamber, to a tem- F. Residual liquid from the separating chamber preceding the fractionating stage of the system is returned to the coking zone. This operation may produce, per barrel of charging stock, approximately 50 per cent of motor fuel having an octane number of approximately '74., by the motor method,

and approximately pounds of petroleum coke of good structural strength and relatively low volatility, the remainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

1. In the conversion of hydrocarbon charging oil containing residual components of petroleum, the process which comprises subjecting relatively clean reflux condensate, unadmixed with residual components of the charging oil, to cracking conditions of temperature and pressure in a heating coil, discharging the resultant cracked products into an externally unheated separating chamber, introducing said charging oil, at below cracking temperature, into the chamber and therein vaporizing a substantial portion thereof by the heat of the cracked products, separating the commingled materials in the chamber into vapors and residue, removing unvaporized oil from the chamber and subjecting the same to further distillation, thereby forming additional vapors, passing the first-named vapors and said additional vapors in indirect heat exchange relation with said charging oil prior to introduction of the latter to the chamber to preheat the charging oil and to separate high-boiling components of the vapors, then supplying the remaining vapors to a second heating zone and heating the same therein to higher cracking temperature than the reflux condensate in said coil, fractionating the cracked vapors from the second heating zone to condense heavier fractions thereof and supplying such condensed fractions to the coil as said reflux condensate, and finally condensing the fractionated vapor.

2. A hydrocarbon oil conversion process which comprises heating relatively clean reflux condensate formed in the process to cracking temperature under pressure in a heating coil and discharging the resultant products into a separating chamber, introducing heavy charging oil for the process to said chamber and partially vaporizing the same therein, separating the commingled material in the chamber into vapors and unvaporized oil, subjecting the latterin a second heating coil to independently controlled cracking conditions of temperature and pressure, combining resultant vapors with commingled cracked vapors and charging oil vapors separated in said chamber, subjecting the admixed vapors to vapor phase cracking conditions in a third heating zone, fractionating the vaporous products of the 1ast named step to condense heavier fractions thereof and supplying such condensed fractions to the first-named coil as said reflux condensate,rand finally condensing the fractionated vapors.

3. A hydrocarbon oil conversion process which comprise-s heating relatively clean reflux condensate formed in the process to cracking temperature under pressure in a heating coil and discharging the resultant products into .a separating chamber, introducing heavy charging oil for the process to said chamber and partially vaporizing the same therein, separating the commingled materials in the chamber into vapors and unvaporized oil, subjecting the latter in a second heating coil to independently controlled cracking conditions of temperature and pressure and then reducing the same to coke in a second chamber, combining vapors evolved in said second chamber with commingled cracked'vapors and charging oil vapors separated in the firstmentioned chamber, subjecting 'the admixed vapors to vapor phase cracking conditionsin' a third heating zone, fractionating the vaporous products of the last-named step to condense heavier fractions thereof and supplying such condensed fractions to the first-named coil as said reflux condensate, and finally condensing. the fractionated vapors. H

4. The process as defined in claim 3 further characterized in that high-boiling components are separated from the vapors evolved in the second chamber prior to the introduction of these vapors to the third heating zone.

5. The process as defined in claim 3 further characterized in that the total vaporous products from both said chambers are combined, the mixture cooled to separate high-boiling components thereof and the thus cleaned vapors supplied to the third heating zone.

6. The process as defined in claim 2 further characterized in that the charging oil, prior to its introduction to the chamber, is passed in indirect heat exchange with vapors being supplied to the third heating zone.

7. A process for the conversion of hydrocarbon oils which comprises subjecting intermediate conversion products of the process, comprising insuificiently converted components of the vaporous conversion products recovered therefrom by fractionation, to conversion temperature at superatmospheric pressure in a heating coil, introducingthe heated products into a separating chamber and commingling therewith hydrocarbon oil charging stock for the process, separating the commingled charging stock and conversion products in said separating chamber into vapor,- ous and liquid components, withdrawing said vaporous components from the separating chamber, removing therefrom undesirable higheboiling materials, subjecting the remaining vapors to further conversion at an appreciably higher temperature in a separated heating coil, separating the resulting vaporous and residual liquid conversion products, subjecting the former to fractionation for the removal therefrom of said insufliciently converted components which are supplied to the first mentioned heating coil for conversion, subjecting fractionated vapors of the desired end-boiling point to condensation, collecting the resulting distillate, Withdrawing said liquid components of the charging stock and conversion products from said separating chamber, heating the same in a separate heating coil to a temperature sufficient to effect their subsequent reduction to coke, introducing the heated mate-'- rials intoa coking chamber wherein vapors are evolved and wherein said coke is allowed to accumulate and commingling the vaporous products from the coking chamber with said vaporous components from said separating chamber prior to the removal therefrom of said undesirable high-boiling materials.

KENNETH SWARTWOOD. 

